#include <assert.h>
#include <string.h>
#include <stdio.h>

char* my_strcpy(char* dest, const char* src) {
    assert(dest != NULL);
    assert(src != NULL);
    char* p = dest;
    while((*(dest++) = *(src++))) {
        ;
    }
    return p;
}

int main() {
    char dest[30] = "hello, world! hello!";
    char src[] = "hello, world!";
    my_strcpy(dest, src);
    printf("%s\n", dest);
    return 0;
}